Enhancing today's networking technology is a perpetual goal in the communications industry. As the raw speeds of large-scale and personal computing devices soar, the tremendous increase in data transmission demands continue to push the networking bandwidth envelope to capacity. As bandwidth-intensive multimedia content continues to gain popularity and course the veins of the Internet, the unrelenting bandwidth dilemma is no less urgent today than yesterday. This demand has fueled the need for high-bandwidth broadband systems.
The term “broadband” has often been used to describe high-bandwidth transmission of data signals, such as data, video, voice, video conferencing, etc. Broadband philosophies often address networking principles applicable to the backbone of the networking system, since the networking backbone generally faces the highest bandwidth demands. There are many competing technologies for delivering broadband access. For example, there are a number of standards used in digital telecommunications, including TCP/IP, Ethernet, HDLC, ISDN, ATM, X.25, Frame Relay, Digital Data Service, FDDI (Fiber Distributed Data Interface), T1, xDSL, Wireless, Cable Modems, and Satellite among others. Many of these standards employ different packet and/or frame formats. The term “frame” is often used in reference to encapsulated data at OSI layer 2, including a destination address, control bits for flow control, the data or payload, and CRC (cyclic redundancy check) data for error checking. The term “packet” is often used in reference to encapsulated data at OSI layer 3. Further, the term “cell” is often used in reference to a group of bytes/octets conditioned for transmission across a network. However, it should be understood that for purposes of the present application, the terms packet, frame, and cell may be used interchangeably to refer to groups or collections of data. Further, a packet format or frame format generally refers to how data is encapsulated with various fields and headers for transmission across the network. For example, a data packet typically includes a destination address field, a length field, an error correcting code (ECC) field or cyclic redundancy check (CRC) field, as well as headers and trailers to identify the beginning and end of the packet. The terms “packet format” and “frame format”, also referred to as “cell format”, are generally synonymous for purposes of this application.
Packets transmitted across a network are associated with a transmission protocol. A protocol is a set of rules that governs how devices on a network exchange information. Packets traversing the network may be of differing formats or “protocols.” This is often due to the development of incompatible proprietary protocols by computer manufacturers. While protocol compatibility and standardization are becoming increasingly important, even standard protocols provide multiple options and are not always interchangeable between applications. Further, new protocols will continue to be developed to address certain network limitations, or to otherwise improve network data transmission. All of these factors contribute to the reality that multiple transmission protocols exist, and will likely continue to exist.
Examples of typical protocols used to communicate information include the Internet Protocol (IP), which is a “best-effort,” connectionless protocol responsible for delivering data from host to host across a network such as the Internet. IP is a predominant protocol used to transmit data across the Internet. Other protocols are used to transmit packets across the Internet as well, such as Framed ATM over SONET/SDH Transport (FAST) and IP on multiprotocol label switching (MPLS). FAST is a new protocol intended to improve the performance of asynchronous transfer mode (ATM). FAST introduces a variable length user data field, while preserving the proven advantages of ATM, such as real quality of service guarantees, the security and traffic isolation provided by virtual connections, network management, traffic management, control mechanisms for bandwidth on demand, etc. MPLS integrates layer-2 information about network links into layer-3 (IP) within a particular autonomous system in order to simplify and improve IP-packet exchange. MPLS essentially provides connection-oriented labeling in an otherwise connectionless environment, which has resulted in MPLS being considered associated with layer-2.5. With MPLS, different flows can be classified, and different service levels can be associated with the different flow classifications.
As described above, packets transmitted on a network such as the Internet may be associated with one of a number of different protocols, and thus packets associated with different protocols may be received at a given node, switch, router, etc. As described more fully below, the introduction of multiple packet protocols at a node requires special consideration when the entire data flow is subject to editing as the packets traverse the network.
Packets, frames, cells, and/or other data units traversing a network such as the Internet often face the possibility of being modified at a given network node. A variety of situations may result in a need to modify or “transform” the packet. For example, a packet reaching a node may need to be redirected from its original course to an alternate course. This can occur where an originally-intended node along the path becomes unavailable due to server problems, transmission cables being cut or otherwise damaged, and the like. In such a case, a “destination address” identified in a packet may require modification to alter the path of the packet in its quest to reach the ultimate destination. Another example of packet editing include the potential need to change header fields of the packet, such as packet length and checksum fields. If, for example, a packet is modified for any reason, the checksum and/or packet length fields are very likely to change, resulting in the need to further modify the packet to update such fields. Other fields include the time-to-live (TTL), packet conformance indicators such as colorations and drop priorities, etc. As can be seen, packets may require editing as they navigate the network towards their respective destination nodes.
At a particular network node or other ingress point, individual packets that make up a communications traffic stream can be classified into several flows or connections. Further, the traffic stream flows may include packets being transmitted in connection with different protocols. This can pose a challenge to editing systems, and typically requires that each of the flows be discretely handled. Due to very high data transmission speeds in today's networks, editing methods have conventionally required custom solutions, generally in the form of specialized, proprietary hardware engines in application-specific integrated circuits (ASICs). Because information may be transmitted across networks (e.g., the Internet) using a variety of different networking protocols, multiple specialized circuits are generally required to accommodate packets of each packet protocol that might traverse the network switch, router, bridge, or other intermediate system between the source and destination. For example, a separate packet transformation methodology, and therefore separate ASIC, may be required for each packet protocol used in the network. This results in higher costs, part counts, and general complexities, while adversely impacting system efficiencies.
Accordingly, there is a need in the communications industry for a method and apparatus for commonly transforming one or more packet flows of multiple transmission protocols. The pre~sent invention fulfills these and other needs, and offers other advantages over the prior art policing approaches.